The effect of moderate consumption of non-nutritive sweeteners on glucose tolerance and body composition in rats.

Glucose tolerance and body composition were determined in male rats given non-nutritive sweeteners (NNS) (aspartame or sucralose) in drinking water. Areas under the curve for glucose and insulin with NNS did not differ from control. NNS treatment had no effect on weight gain or percent body fat. Epididymal fat pad mass was higher with aspartame and the ratio of trunk to total fat was less with sucralose versus control, suggesting that NNS consumption altered body fat distribution.

Academy of nutrition and dietetics: revised 2014 standards of practice and standards of professional performance for registered dietitian nutritionists (competent, proficient, and expert) in sports nutrition and dietetics.

Sports nutrition and dietetics addresses relationships of nutrition with physical activity, including weight management, exercise, and physical performance. Nutrition plays a key role in the prevention and treatment of obesity and chronic disease and for maintenance of health, and the ability to engage in physical activity, sports, and other aspects of physical performance. Thus, the Sports, Cardiovascular, and Wellness Nutrition Dietetic Practice Group, with guidance from the Academy of Nutrition and Dietetics Quality Management Committee, has developed the Revised 2014 Standards of Practice and Standards of Professional Performance as a resource for Registered Dietitian Nutritionists working in sports nutrition and dietetics to assess their current skill levels and to identify areas for further professional development in this emerging practice area. The revised document reflects advances in sports nutrition and dietetics practice since the original standards were published in 2009 and replaces those standards. The Standards of Practice represents the four steps in the Nutrition Care Process as applied to the care of patients/clients. The Standards of Professional Performance covers six standards of professional performance: quality in practice, competence and accountability, provision of services, application of research, communication and application of knowledge, and utilization and management of resources. Within each standard, specific indicators provide measurable action statements that illustrate how the standards can be applied to practice. The indicators describe three skill levels (competent, proficient, and expert) for Registered Dietitian Nutritionists working in sports nutrition and dietetics. The Standards of Practice and Standards of Professional Performance are complementary resources for Registered Dietitian Nutritionists in sports nutrition and dietetics practice.

The effects of adding leucine to pre and postexercise carbohydrate beverages on acute muscle recovery from resistance training.

The present study examined the effects of adding leucine to pre and postexercise carbohydrate beverages on selected markers of muscle damage, delayed-onset muscle soreness (DOMS), and squat performance for up to 72 hours after lower-body resistance training. Seventeen resistance trained men (mean +/- SD age 22.9 +/- 2.9 years) and 3 resistance trained women (mean +/- SD age 21.6 +/- 2.6 years) performed 6 sets of squats to fatigue using 75% of the 1 repetition maximum. Each subject consumed a carbohydrate beverage 30 minutes before and immediately after exercise with or without the addition of 22.5 mgxkg (45 mgxkg total) of leucine in a randomized, double-blind fashion. Serum creatine kinase (CK), lactate dehydrogenase (LDH), and DOMS were analyzed immediately before (TIME1), 24 (TIME2), 48 (TIME3), and 72 (TIME4) hours after exercise. The subjects repeated the squat protocol at TIME4 to test recovery. No differences were observed between groups for squat performance, defined as the total number of repetitions performed during 6 sets of squats, for both TIME1 and TIME4. The addition of leucine did not significantly decrease CK and LDH activity or DOMS. These results suggested that adding leucine to carbohydrate beverages did not affect acute muscle recovery and squat performance during both initial testing and during a subsequent exercise bout 72 hours later in resistance trained subjects.

Effect of a high protein diet on glucose tolerance in the rat model.

The purpose of this study was to determine the effects of a high protein diet on glucose tolerance. Nine Sprague Dawley rats received a high protein (HP) diet (65% protein, 35% fat) and eight rats consumed a standard chow (SC) diet over eight weeks. Oral glucose tolerance tests (OGTT) were performed at the end of the third and the seventh week. The diet did not effect glucose tolerance in the first (SC=10357+/-294 mg/dl/120 min; HP=9846+/-300 mg/dl/120 min) or the second OGTT (SC=10134+/-395 mg/dl/120 min; HP=10721+/-438 mg/dl/120 min) as reflected by the area under the glucose concentration curve. Similarly, the area under the insulin concentration curve was not effected by the high protein diet during the first (SC=49.21+/-8.46 ng/ml/120 min; HP=41.75+/-10.54 ng/ml/120 min) or the second OGTT (SC=96.63+/-13.68 ng/ml/120 min; HP=92.77+/-17.44 ng/ml/120 min). The high protein diet group experienced a delayed glucose response for the first (SC=30 min at 112+/-7 mg/dl; HP=60 min at 101+/-5 mg/dl) and second OGTT (SC=15 min at 117+/-5 mg/dl; HP=60 min at 95+/-7 mg/dl). Body mass increased to the same extent in each diet group from the initial to final weighing (SC=159+/-2 g to 254+/-7 g; HP=157+/-2 g to 242+/-7 g). Despite a delay in peak glucose response, these findings suggest that glucose tolerance and body mass were neither adversely nor positively affected by a high protein diet.

The Yale Physical Activity Survey for older adults: predictions in the energy expenditure due to physical activity.

OBJECTIVE: To evaluate the accuracy of the Yale Physical Activity Survey (YPAS) for older adults. DESIGN: Fourteen-week strictly controlled diet study. SUBJECTS/SETTING: Eleven men and 17 women, age range 55 to 78 years, spent 10 weeks in an outpatient setting and 4 weeks in an inpatient setting at the General Clinical Research Center, Noll Physiological Research Center, The Pennsylvania State University, University Park. INTERVENTION: Subjects were provided dietary energy to maintain body weight within +/-0.5 kg of baseline weight. The daily menus contained 0.8 g protein per kilogram body weight and nonprotein energy as 60% carbohydrate and 40% fat. MAIN OUTCOME MEASURES: Metabolizable energy intake (MEI) was measured at week 14 from the gross energy contents of food, urine, and feces, with corrections for any body composition changes during the last 6 weeks of weight maintenance. Resting energy expenditure (REE) was determined using indirect calorimetry. The thermic effect of feeding (TEF) was estimated to be 10% of the MEI. The energy expenditure due to physical activity (EEPA) was derived by the formula: EEPA=MEI-REE-TEF. This value was compared with the EEPA estimated from the YPAS. Statistical analyses performed Two-factor analysis of variance with repeated measures and paired t tests. RESULTS: At week 14, after a minimum of 6 weeks of sustained weight stability, the derived EEPA was not different from that estimated using the YPAS for the men and the men and women combined, while the YPAS estimate was more than the measured mean value for the women (P<.05). There was wide variability in the accuracy of the EEPA prediction for individual subjects (range=-637 to 794 kcal). APPLICATIONS/CONCLUSIONS: The YPAS may be used, with caution, to estimate the EEPA for groups of older individuals, and may provide inaccurate estimates of the EEPA in older individuals.

The antioxidants--vitamin C,vitamin E, selenium, and carotenoids.

This is the second in a series of articles reviewing the recent revisions of the Recommended Dietary Allowances (RDA) and the resulting Dietary Reference Intakes (DRI). In April of 2000, the Food and Nutrition Board of the National Academy of Sciences released Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. The central premise of the report did not perpetuate the prevailing popular thought that large doses of antioxidants will prevent chronic diseases. Instead the panel concluded that at this time, insufficient scientific evidence exists to sustain claims that ingesting megadoses of dietary antioxidants can prevent certain chronic illnesses such as cardiovascular disease or cancer. In some instances recommended nutrient levels were reduced from the previous report in 1989; e.g., for the first time upper tolerable levels of ingestion (UL) were established to prevent the harmful effects of over consumption of essential nutrients, such as vitamin C, vitamin E, and selenium. Although dietary recommendations do exist for vitamin A, the panel did not set recommendations for beta-carotene or the other carotenoids due to lack of sufficient research to support recommended intakes or upper tolerable levels of intake. However, the panel advises the public to avoid intakes of provitamin A compounds, such as the numerous carotenoids, beyond the levels required to prevent vitamin A deficiency. Changes were also made with regard to estimating the amount of provitamin A carotenoids required to make a unit of retinal. The revised estimate suggests a twofold higher conversion rate than previously believed. Although this comprehensive report on the dietary reference intakes for vitamin C, vitamin E, selenium, and the carotenoids did not decisively confirm the role of antioxidants for the prevention of chronic diseases in humans, many research studies have generated new data to support this concept. Additional research is needed to define the attributes of antioxidants as studies progress from in vitro and animal studies to human nutrition.

The Atwater energy equivalents overestimate metabolizable energy intake in older humans: results from a 96-day strictly controlled feeding study.

The Atwater energy equivalents of 16.7, 16.7 and 37.7 kJ/g of protein, carbohydrate and fat, respectively, are the standard values used to calculate the macronutrient intakes required to meet a person's metabolizable energy requirement. The aim of this study was to compare in older people the measured metabolizable energy intake (MEI(MEAS)) required to achieve and maintain stable body weights with the MEI estimated using the Atwater energy equivalents (MEI(AT)). During a 96-d (14-wk) strictly controlled dietary period, 11 men and 17 women (55-78 y old) were each provided a MEI(AT) to maintain body weight within +/- 0.5 kg of baseline weight. The MEI(MEAS) was determined retrospectively from the gross energy contents of food, urine and feces samples collected during week 14. Resting energy expenditure was measured using indirect calorimetry. At wk 14, MEI(AT) overestimated MEI(MEAS) by 26%. These results suggest that the Atwater energy equivalent values may overestimate the actual MEI of older people.

Lower body versus whole body resistive exercise training and energy requirements of older men and women.

A person's energy requirement is defined as the metabolizable energy intake (MEI) consumed over a period of body weight stability. Controversy exists regarding whether resistive exercise training (RT) influences the energy requirement of older people. The aim of this study was to assess the effect of RT on the energy requirement of older people. The subjects were 11 men (M) and 17 women (W); age range, 55 to 78 years. During a 14-week precisely controlled diet study, each subject consumed foods and beverages portioned to provide sufficient MEI to match their energy requirement and to keep body weight stable at +/- 0.5 kg of their starting weight. MEI was determined from bomb calorimeter analyses of the gross energy (GE) content of food, urine, and feces samples collected during 4-day intake-balance periods at study weeks 2, 8, and 14 (baseline, week RT6, and week RT12, respectively). MEI = GE(food)-GE(urine) - GE(feces). Resting energy expenditure (REE) was measured using an indirect calorimeter. From study weeks 3 to 14, 10 subjects (4 M, 6 W) remained sedentary (SED), 9 subjects (4 M, 5 W) performed lower body RT (LBRT) 3 times/week, and 9 subjects (3 M, 6 W) performed whole body RT (WBRT) 3 times/week. Body weight was not different among the SED, LBRT, and WBRT groups at baseline and were not changed over time or influenced by RT. At baseline, MEI was not different among the 3 groups. From weeks RT1 to RT12, MEI had to be increased by 17% +/- 5% (mean +/- SEM), 14% +/- 7%, and 12% +/- 7% in the SED, LBRT, and WBRT groups, respectively, to maintain stable body weights. At week RT12, the MEI required to maintain stable body weight was not significantly different among the SED, LBRT, and WBRT groups (9.45 +/- 0.95, 9.40 +/- 0.83, and 8.64 +/-0.53 MJ/d, respectively). At week RT12, the MEI and MEI/REE ratio were higher in men versus women, independent of group assignment. These data suggest that RT, whether performed using the lower body only or the whole body, does not increase the energy requirement of older people. Also, these data show that the energy requirement of older men is greater than that of older women.

Dietary protein adequacy and lower body versus whole body resistive training in older humans.

This study assessed the effects of long-term consumption of the United States Recommended Dietary Allowance (RDA) for protein by older people who were sedentary or performed resistive training (RT) on body composition, skeletal muscle size and protein metabolism, and if the number of muscle groups trained influenced the muscle hypertrophy response to RT. Twelve men and 17 women (age range 54-78 years) completed this 14 week controlled diet and exercise study. Throughout the study, each subject completely consumed daily euenergetic menus that provided the RDA of 0.8 g protein kg(-1) day(-1). From study weeks 3-14 (weeks RT1-RT12), 10 subjects (four men, six women) performed whole body RT (WBRT), nine subjects (four men, five women) performed lower body RT (LBRT) and 10 subjects (four men, six women) remained sedentary (SED). Both the LBRT and WBRT groups performed knee extension and flexion exercises, and the WBRT group also performed chest press and arm pull exercises (three sets per exercise at 80 % of one repetition maximum, 3 days per week for 12 weeks). From week 2 (baseline) to week RT12, muscle strength increased in muscle groups trained in the LBRT and WBRT groups, and was not changed in the SED group. From baseline to week RT12, whole body muscle mass and protein-mineral mass were not changed, fat-free mass (P = 0.004) and total body water (P = 0.013) were decreased, and percentage body fat was increased (P = 0.011) in these weight-stable older people, independent of group assignment. The RT-induced increases in mid-thigh muscle area (from computed tomography scans) were comparable in the LBRT and WBRT groups (2.13 +/- 1.26 cm(2) and 2.17 +/- 1.24 cm(2), respectively), and were different from those in the SED group, which lost muscle area (-1.74 +/- 0.57 cm(2); group-by-time P < 0.05). From baseline to week RT12, 24 h urinary total nitrogen excretion decreased (P < 0.001), nitrogen balance shifted from near equilibrium to positive, whole body leucine oxidation (from the infusion of L-[(13)C]leucine) decreased (P < 0.05) and net (postabsorptive vs. postprandial) leucine balance (P < 0.05) increased from near equilibrium to positive, with no differences in responses over time among the three groups. In conclusion, the number of muscle groups trained did not influence whole body protein metabolism or RT-induced muscle hypertrophy in older people. Most of these data are consistent with a successful adaptation to the RDA for protein. However, research should continue to question whether the decreases in fat-free mass and total body water observed in all subjects, and the decrease in mid-thigh muscle area in the SED group, are physiological accommodations, and whether the RDA for protein might be marginally inadequate for older people to maintain skeletal muscle.

Recommended dietary allowances--then and now: a review.

This is the first in a series of articles reviewing the recent revisions of the Recommended Dietary Allowances (RDA) and the resulting Dietary Reference Intakes (DRI). In the United States our nutrient guidelines have had far reaching applications to human health and agricultural practices. The broad use of the previous edition of the Recommended Dietary Allowances has necessitated a complete reevaluation of the criteria, uses and reporting of nutrient guidelines. The resulting documents, a series of reports collectively referred to as the Dietary Reference Intakes, are being released over a number of years, beginning in 1997 and expected to be completed by the year 2003.